1. Field of the Invention
The present invention relates to image processing in displaying a document image.
2. Related Background Art
Conventionally, in display control for displaying documents prepared by various applications on a screen, in the case where scroll of a displayed part on a screen or re-drawing of a part hidden behind another window is performed, off-screen images (images prepared by developing drawing elements off-screen (on a virtual screen), are stored in an internal memory (off-screen buffer for storing off-screen data) in order to perform drawing quickly.
However, in the conventional system, since no off-screen image is stored in the internal memory (off-screen buffer) when drawing is performed for the first time, an overall off-screen image is created first and then transferred onto the screen (on-screen) to perform drawing. Thus, there is a problem in that, for example, a user cannot check the image until the overall off-screen image is created, and particularly when working on a document requiring longer time for drawing, the user becomes displeased and wonders if the application has become hung-up or frozen.